Shortage of nice guys (5)
I believe the answer is:
gents
'shortage of nice guys' is the definition.
The answer and definition can be both people as well as being plural nouns.
Perhaps there's a link between them I don't understand?
This is all the clue.
Can you help me to learn more?
(Other definitions for gents that I've seen before include "Male loos" , "Public convenience" , "Men (colloq.)" , "toilet" .)